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Observations on Coupling Bumps and Beam Sizes at Lattice SK5 & C12 (BAR)

Analysis of data showing sizeable coupling bumps and beam sizes at lattice SK5 & C12 (BAR) with relevant measurements and conclusions for addressing coupling issues.

demetria-richmond
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Observations on Coupling Bumps and Beam Sizes at Lattice SK5 & C12 (BAR)

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  1. Some PSK Lattice ObservationsU. Wienands, April 23, 07 • Coupling bumps • Beam Sizes

  2. SK5 & -5 mm bump C12(BAR) Sunday 2pm

  3. SKG1

  4. Dispersion • Sizeabley upstream (SK5 bump!)

  5. Beam Sizes • @ LER SXM • ßx ≈ 5.1 m, ßy ≈ 27 m (ßy meas’d) • x ≈ 0.34 m, y ≈ 0.01 m (y upper limit, from meas.) • dp/p = 6.3E-4 • => in x, 0.4 mm for 24 nmr • => in y, 0.2 mm for 1.5 nmr

  6. volume Major (x) Minor (y) Peak (x)

  7. Analysis of data: • x,min ≈ 29 nmr (possible) • y,min ≈ 2.7 nmr (unlikely, but…)

  8. IP beam sizes • Measurements: • ∑minor = 7.9 µm • ∑major = 150 µm • ß*x,HER = 24 cm, ß*x,LER = 60 cm • ß*y,HER = 9.7mm, ß*y,LER = 8.1mm • Use meas’d LER emitt, 50/1.5 nmr for HER, meas’d ß* to estimate ∑: • ∑x = 170 µm, ∑y = 6 µm (6.5 µm if ß*y=10 mm) • ∑x ok since dyn. ß reduces meas’t, • ∑y too small • ß*y,eff maybe higher => coupling issue (??)

  9. BaBar Beam Sizes • What’s up with bunch length??

  10. Conclusion • Fundamentally the new optics works • Lsp ≈ 5 at low currents, > 4.4 starting point. • Local C12(bar) looks ok. • We will need to address the SK5 coupling bump • With luck, SK5 & SKG1 make a closed wave • LER vertical emittance not yet really small • ∑minor measured is too big for beam sizes, ß*y • > may indicate local coupling issue

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